(a) Field of the Invention
The present invention relates to a system and a method for controlling an automatic cruise control of a hybrid vehicle.
(b) Description of the Related Art
Hybrid vehicles (hybrid electric vehicles) use at least two power sources (e.g., an internal combustion engine and battery power). In an electric hybrid vehicle, power from the engine and an electric motor are used to provide power to the drivetrain.
The hybrid vehicles may include, for example, as shown in FIG. 1, an engine 10, a motor 20, an engine clutch 30 connecting/disconnecting power between the engine 10 and the motor 20, a transmission 40, a differential gear system 50, a battery 60, an integrated starter-generator 70 starting the engine 10 or generating electricity by the output from the engine 10, and wheels 80.
Further, the hybrid vehicles may include an HCU (Hybrid Control Unit) 200 that controls the entire operation of the hybrid vehicle, an ECU (Engine Control Unit) 110 that controls the operation of the engine 10, an MCU (Motor Control Unit) 120 that controls the operation of the motor 20, a TCU (Transmission Control Unit) 140 that controls the operation of the transmission 40, and a BCU (Battery Control Unit) 160 that controls and managing the battery 60.
The BCU 160 is sometimes referred to as a BMS (Battery Management System). The integrated starter-generator 70 is sometimes referred to as an ISG (integrated starter & generator) or an HSG (hybrid starter & generator).
The hybrid vehicles are often operated in a plurality of different modes such as an EV mode (Electric Vehicle mode) that is an electric vehicle mode using only the power from the motor 20, an HEV mode (Hybrid Electric Vehicle mode) using the torque from the engine 10 as the main power source and the torque from the motor 20 as a sub-power source, and an RB mode (Regenerative Braking mode) which collects braking and inertia energy by means of electricity generation from the motor 20. The RB mode charges the battery 60, when the vehicles are braked or driven by the inertia. The hybrid vehicles (like other conventional vehicles) may be equipped with an automatic cruise control system that maintains the traveling vehicle speed of the vehicle at a predetermined target vehicle speed (target vehicle speed) without as the driving having to operate the accelerator pedal or the brake pedal.
FIG. 2 shows a schematic configuration of an automatic cruise control system of a hybrid vehicle according to an exemplary embodiment of the related art. The automatic cruise control system of a hybrid vehicle according to an exemplary embodiment of the related art, in automatic cruise control, calculates driver request toque by means of a speed control unit 5 and performs automatic cruise control by producing an engine torque instruction and a motor torque instruction from the calculated driver request torque and provides instructions to the engine and the motor included in a control target 7. The automatic cruise control system of a hybrid vehicle according to an exemplary embodiment of the related art can rapidly change the engine torque instruction to provide an accurate target vehicle speed, when the request torque rapidly changes.
Accordingly, the automatic cruise control system of a hybrid vehicle according to an exemplary embodiment of the related art opens the engine throttle at a predetermined level and changes the spark timing to cope with the rapidly changed engine torque instruction, which may deteriorate the fuel efficiency. Thus, there is a need for a more fuel efficient automatic cruise control system.
The Description of the Related Art is made to help understanding the background of the present invention and may include matters out of the related art known to those skilled in the art.
The above information disclosed in this Background section is only for is enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.